Stencil sheet having transferable back coating



Feb. 7, 1961 R. GUMBINNER 2,970,931

STENCIL SHEET HAVING TRANSFERABLE BACK COATING Filed March 25, 1957INVENTOR. faas'er y/va/xy/v'f BY W K United States PatentO i STENCILSHEET HAVING TRANSFERABLE BACK COATING Robert Gumbinner, Tarrytown,

chrome Corporation, New York Filed Mar. 25, 1957, Ser. No. 648,250

3 Claims. (Cl. 117-355) N.Y., assignor to Poly- Yonkers, N.Y., acorporation of ing ink may flow.

It is known to assemble such stencil sheets by adhesively securing onemarginal edge thereof to a carbon cushion sheet and to a backing sheet.The purpose of the carbon cushion sheet is to provide a contrast invisibility when typing the stencil and also to produce an impression ona backing sheet which can then be used as aproof copy or for otherdesired purposes. For example, the stencil and carbon backing sheet aresometimes attached to an invoice form so that, when the stencil istyped, a copy is obtained on the invoice and the stencil can then beused in a hand stamp or otherwise to provide copies on packingcontainers.

Prior to the present invention, it was not possible to successfullyprovide a stencil assembly of this type which would eliminate thenecessity for a separate carbon sheet. However there is now provided onthe backof the stencil sheet itself a dark, impression-transmittingcoating which in a farmore simple andeconomical fashionperforms .thefunction of the separate carbon sheet heretofore. necessary. i 4'Previous attempts tocoat the backing sheet of a stencil? assembly with acarbonizedmaterial; have not proven successful, because the oils in thestencil coating tended to soften the. carbon on the backing material.fl?hll s, while contrast would be obtained during the typing ohefstencil, it would 'not be, possible by such methods to obtain thetype 'ofpro'o'f co'py referred to above.

Accordingly, it is an object of the present invention to provide astencil assembly which includes a stencil sheet having a dark,image-transmitting coating on one surface thereof which will perform thefunction of the extra carbon sheet heretofore necessary.

Another object is to provide a stencil assembly which includes animage-transmitting stencil sheet and a backing sheet upon which a proofcopy may be formed simultaneously with the cuttingof the stencil.

These and other objects of my invention will become apparent from thefollowing description when taken in connection with the drawing, .inwhich the single figure is a perspective view showing the constructionof the stencil as it would appear with the stencil sheet in thepartially removed position.

Essentially the present invention is directed to a stencil sheetcomprising a base tissue having a pastel-colored stencilizable coatingon the surface thereof which is to receive the impression from thetypewriter, stylus or the like. On the opposite, or back surfacethereof, a

which -is in direct contact with the backing sheet, is pro- 2,970,931Patented Feb. 7, 1961 ice carbon, impression-transmitting coating isprovided. Although this coating typically, but not necessarily, includesa carbon type pigment, for the sake of simplicity it will hereinafter bereferred to as the carbon coating.

This stencil sheet is readily fastened to a suitableimpression-receiving backing material by providing, on one marginal edgethereofQa coating of a pressure sensitive adhesive which allowsthestencil to be removably secured to the backing.

Thus, when making stencils in accordance with the stencil sheet andassembly herein disclosed, the carbon coating on the back of the stencilsheet provides sharp contrast with the pastel coated surface normallyvisible to the stencil cutter and at the same time allows for theproducion of carbon proof copies on the impression receiving backingsheet.

Referring now to the drawing, it is seen that stencil sheet 10 may beremovably secured to backing sheet 11 by means of the pressure sensitiveadhesive strip 12, so that after the stencil is cut, the stencil :sheetis readily removed from the backing. The backing sheet also is readilydetachable by means of perforations 16. It is also seen from the figurethat there is produced on the backing sheet a carbon impression 18 ofthe stencil which was cut.

The pastel coating which is applied to the normally visible or outsidesurface 14 of the stencil sheet .will

typically be an oil-fatty acid-nitrocellulose mixture having 1 includedtherewith the desired light colored pigment in suitable proportions. Anexample of a suitable composition for the pastel'colored coating is asfollows:

In. addition to the above, of course various stabilizers andplasticizers such as tricresyl phosphate, phenol, chlorinatednaphthalene may be used.

.The pigment which may be used to impart the desired pastel color wouldbe lead chromate, titanium dioxide, Hansa yellow or other lightershades. i

In applying this coating, the pigment is first ground thoroughlyon athree roll mill in a portion of the oil. The nitrocellulose is dissolvedin a mixture of active and latent solvents such as ether, ethyl alcohol,butyl acetate, methyl acetate, acetone, ethylene glycol, monoethyl'ethers, ethyl ethers, ethyl lactate, isopropyl alcohol. Other; solventssuch as are typicallyused in lacquer formulations may also beused; it

In addition to the above, a hydrocarbon diluent may be used inquantities sufficiently limited not to upset the gel formation necessaryfor the production of a good stencil coating.

The pastel coating is preferably applied to the stencil sheet before thecarbon coating. In order to make sure that the pastel coating is appliedonly to one side of the fiber sheet, it is necessary to set this coatingrapidly after the application of the coating solution. Since the coatingmay be applied at various temperatures, there are many solvents whichmay be selected which are sufiiciently volatile to provide the necessaryrapid setting. For example, using temperatures of the order of F., ethylalcohol and ether would be suitable solvents while at highertemperatures up to about 250 F. higher boiling solvents may be selectedto obtain the same desired results.

The opposite or back side of the stencil sheet 15, which .is notnormally visible to the stencil cutter and applied to the stencil sheetso mm 94 A a i 3 i a dark. p qnran mittin matin which would typicallyhave the following composition.

, Note thatin the carbon coating, the ratio, of nitrocellulose to thefatty acid. and oil is higher thaniinithe, pastel coating; This isnecessary to make a relatively hard coating; which will'givea sharpimpression on the copy paper and will not result in a broad splash orblurred car on i f he e 1 In applying this carbon coating to the stencilsheet, the same solvents as used with the pastel coatings may be used,except that the percentageof the-latent solvents should'be hi'gherinorder that thiscoat does not attack n'interaet with the previouslyapplied pastel coating. 1

The dark pigments which are used in the impression: transmitting coatingare commonly black pigments such a carbon black, lamp black or Peerlessblack. In fiddle tion; to the above, blue pigments such as iron blue canbeused and, if desired, a green pigment such as a mix: ture of iron blueand a yellow-pigment may also be used to give a satisfactory color andsufficient density for good visibility. It-is, of course, necessary tolimitthe pigments inboth coatings to those which will not bleed in theoils used tq plasticize the nitrocellulose;

r in addition to the pigments mentioned above, there may also be usedtungstated Victoria blueor a, non-bleed.- ingredpigrnent such as certainLithol reds which are well knewnto the art, r

B oth the-pastel and dark colored pigments should be that a suitableweight of coating is applied on each side thereof' Each gram of basetissue will have on the outside surface thereof about'2.7'to 5.8 gramsof the pastel coating composition and between about .08 to 1.6 grams ofthe carbon coating composition. These quantities-are typically appliedto a stencil sheet eight and a half by sixteen and a half inches whichwill commonly have a weight of the order of one gram. g As previouslymentioned, itis important that the ratio ofoil (including fatty acid) tonitrocellulose should be higher in the pastel coating. Thus in thiscoating, the oil to nitrocellulose ratio will be in the range of about6,511 to 9:1. The carbon coating will have aratio of oil tonitrocellulose in the range of about 4:1 to, 7:1.

In addition to the above, it is of course apparent to one skilled in theart that the oil to nitrocellulose ratio may be dependent to some extenton the viscosity of the coa in compo io It i also ap a ent hat st a awide variety of oil plastieizers and grades of nitrocellur amass;

4, lose which can vary the specific proportions referred to in the aboveexamples. i

By coating the stencil sheet as indicated above, there is provided asingle sheet which eliminates the necessity and therefore the cost of aseparate carbon sheet. This advantage not only reduces manufacturingcosts, but provides for simplicity in handling because there is no needto keep a separate carbon sheet in. alignment withthe stencil and thebacking-sheet.

Although. preferred forms of this invention have been hat-di a ed. itllfnq b ap n to hes s; ssi in the art that many modifications andvariations aybe 7 made, and it, is preferred therefore to be limited,not by the specific disclosure herein, but only by the appended claims.1 9

What is claimed is:

l. A stencil sheet comprising a base tissue, a pastelcoloredstencilizable coating on one surface of saidbase tissue, said coatinghaving an oil to nitrocellulose.- ratio in the range. of about 6.511 to9: 1,' and onthe opp surface of the base tissue, a dark,impression-transmit 'ng eoating having an oil to nitrocellulose ratio inthe range of about 4:1 to 7:1. HM

2. The stencil sheet of claim 1 in which the pastel coloredstencilizable coating is present in an amount of from about 2.7. to 5.0grams per gram of base tissue. and the dark, impression-transmittingcoating is present in an amount between about .08 to 1.6 grams per gramif base tissue. Y I

3. A stencil sheet comprising a base tissue, a pastel; coloredstencilizable coating on one surface of said base tissue, said coatinghaving an oil to nitrocelluloseiratie in the range of about 6.511 to9:1, said coating further being present in amounts of from about 2.7, to5.0, g Iris per gram of base tissue and, on the. oppositev surf thesaidbase tissue, a dark, impression-transmitting ing having an oil tovnitrocellulose ratio in the range of about 4:1 to. 7:1, said coatingfurther being present in an amount of between about '.08 to 1.6 gramsper gram of base tissue. V v 1" References: e m h fil h s an:

UNITED STATES'PATENTS i "1,617,386 Fuerth eb. 15-, 1,645,593 Geiger .4Oct. 13,1921 1,6 64,77 7 Horii Apr. 3, 1928 828,766 De Waele Oct. 27,1931 1,937,75 Elliott Dec. 5, 1933 2,313,810 Dalton Mar. 16, 19432,335,992 Biskind Dec. 1; 1943 FOREIGN PATENTS 92,220 Great Britain May15,1933

424,495] Great Britain s

1. A STENCIL SHEET COMPRISING A BASE TISSUE, A PASTELCOLOREDSTENCILIZABLE COATING ON ONE SURFACE OF SAID BASE TISSUE, SAID COATINGHAVING AN OIL TO NITROCELLULOSE RATIO IN THE RANGE OF ABOUT 6.5:TO 9:1,AND ON THE OPPOSITE SURFACE OF THE BASE TISSUE, A DARK,IMPRESSION-TRANSMITTING